A DTV transmitting system includes two pre-processors. The first pre-processor codes high-priority enhanced data for forward error correction (FEC) and expands the FEC-coded data. The second pre-processor codes low-priority enhanced data for FEC and expands the FEC-coded low-priority enhanced data. The DTV transmitting system further includes a data formatter generating enhanced data packets including the pre-processed data, a multiplexer multiplexing the enhanced data packets with main data packets, an RS encoder RS-coding the multiplexed data packets, a data interleaves interleaving the RS-coded data packets, and a block processor which codes each block of enhanced data in the interleaved enhanced data packets and bypasses the interleaved main data packets.

Claim:

What is claimed is:

1. A method of processing digital broadcast data in a digital television (DTV) transmitter, the method comprising: coding first enhanced data for forward error correction(FEC) at a first coding rate; coding second enhanced data for forward error correction (FEC) at a second coding rate; block processing the coded first and second enhanced data by specific code rates, wherein the specific code rates are 1/2 or 1/4; forming data groups including the block processed first and second enhanced data and inserting place-holders for MPEG headers and place-holders for non-systematic Reed-Solomon (RS) parity into the data groups, wherein at least one of the data groupsincludes first, second and third regions, wherein the second region includes known data sequences; deinterleaving data in the data groups; removing the place-holders for non-systematic Reed-Solomon (RS) parity and replacing the place-holders for MPEGheaders with MPEG headers to generate enhanced data packets including the deinterleaved data; multiplexing the generated enhanced data packets and main data packets including main data to output multiplexed data packets; RS-coding the main data in themultiplexed data packets by a systematic RS encoding scheme; RS-coding the enhanced data in the multiplexed data packets, by a non-systematic RS encoding scheme; interleaving data in the multiplexed data packets in a data interleaver; and trellisencoding the interleaved data in a trellis encoder, wherein a memory in the trellis encoder is initialized prior to each of the known data sequences.

2. The method of claim 1, wherein the deinterleaving is performed by an inverse process of the interleaving.

3. The method of claim 1, wherein the data groups further include signaling information having group information.

4. An apparatus for processing digital broadcast data in a digital television (DTV) transmitter, the apparatus comprising: a first coder configured to code first enhanced data for forward error correction (FEC) at a first coding rate; a secondcoder configured to code second enhanced data for forward error correction (FEC) at a second coding rate; a block processor configured to block process the coded first and second enhanced data by specific code rates, wherein the specific code rates are1/2 or 1/4; a group formatter configured to form data groups including the coded first and second enhanced data and insert place-holders for MPEG headers and place-holders for non-systematic Reed-Solomon (RS) parity into the data groups, wherein atleast one of the data groups includes first, second and third regions, wherein the second region includes known data sequences; a data deinterleaver configured to deinterleave data in the data groups; a packet formatter configured to remove theplace-holders for non-systematic Reed-Solomon (RS) parity and replace the place-holders for MPEG headers with MPEG headers to generate enhanced data packets including the deinterleaved data; a multiplexer configured to multiplex the generated enhanceddata packets and main data packets including main data to output multiplexed data packets; an RS encoder configured to RS-code the main data in the multiplexed data packets by a systematic RS encoding scheme and RS-code the enhanced data in themultiplexed data packets by a non-systematic RS encoding scheme; a data interleaver configured to interleave data in the multiplexed data packets; and a trellis encoder configured to trellis encode the interleaved data, wherein a memory in the trellisencoder is initialized prior to each of the known data sequences.

5. The apparatus of claim 4, wherein the data deinterleaver performs deinterleaving by an inverse process of the data interleaver.

6. The apparatus of claim 4, wherein the data groups further include signaling information having group information.